There is a magnetic disk drive, which is smaller and thinner than 2.5-type or 3.5-type magnetic disk drives used in current personal computers and uses a small-diameter magnetic recording medium as described in JP-A-09-180426.
Portable small-sized magnetic disk drives are made further thinner than the 2.5-type magnetic disk drives. While, for example, the 2.5-type magnetic disk drives have a thickness of 9.5 mm, the thin portable small-sized magnetic disk drives have a thickness of around 5 mm.
FIGS. 4 and 5 show a configuration, in which Voice Coil Motor (hereinafter, referred as VCM) system wires (a coil lead wire and a ground wire) and a Flexible Printed Circuit (hereinafter, referred as FPC) are connected to each other in general magnetic disk drives. Referring to these enlarged views, a FPC ground wire connection portion 303, which is an extension of a FPC 301, is mechanically fixed to a coil holder 300 by a screw 305. The screw 305 is electrically conductive. The screw 305 puts the FPC ground wire connection portion 303 of the FPC 301 between it and the coil holder 300. Thereby, electric connection is made to the FPC ground wire connection portion 303 and the FPC 301 from the coil holder 300 through the screw 305. The reason why the coil holder 300 is connected with ground through the screw 305 and the FPC 301 is to ground (earth) a magnetic head. That is, a magnetic disk, which is connected through a spindle motor with ground, and the magnetic head are put at the same potential whereby the magnetic head is prevented from being electrostatically broken by static electricity generated between the magnetic head and the magnetic disk.
A lead wire extended from a coil 302 is soldered to a FPC connection portion 304, which is an extension of the FPC 301, on an upper surface of the coil holder. Also, in that construction, in which the coil holder 300 is molded from a resin material and the coil 302 is molded to be connected to the coil holder, the lead wire extended from the coil 302 is soldered to the FPC on the upper surface of the coil holder 300.
When the FPC is fixed to the coil holder by a screw to be connected with ground, a thickness corresponding to a screw head is required, which makes it difficult to make a magnetic disk drive smaller and thinner so as to adapt the drive to a portable.
As the magnetic disk drive becomes thinner, it becomes difficult to ensure a sufficient space between the coil holder and a yoke 407 (FIG. 6) of a VCM arranged in opposition to the coil holder. Therefore, the provision of a screw on the coil holder becomes further difficult from a point of view in ensuring a space. Further, accompanying with small sizing of a magnetic disk drive, size of a coil holder itself becomes smaller, whereby it also becomes difficult to ensure that magnitude of a tapped hole, which corresponds to a screw dimension for fixation of the FPC, on the coil holder. Also, it becomes difficult to ensure a space, in which a coil lead wire is soldered on the upper surface of the coil holder.
Also, in the case where a screw is correspondingly made smaller and thinner in size as a drive is made smaller and thinner in size, screw threads must be made small in pitch and height in working of threads. Therefore, working of a screw itself and working of thread grooves cannot be easily done. Further, as a screw becomes smaller, a head of the screw must be made smaller. Then, workability in assembling is worsened to have an adverse influence in terms of cost.
In other words, as a magnetic disk drive is made smaller and thinner in size, a screw cannot but be made correspondingly smaller and thinner in size. When a certain limit is exceeded, however, corresponding small-sizing and thinning of a screw reach limits in terms of strength and structure, so that a screw cannot be put into practical use. Also, magnetic disk drives are constructed such that a VCM yoke covers that upper surface of a coil holder, on which a screw is mounted. Therefore, as magnetic disk drives are made smaller and thinner in size, there is caused a situation, in which a portion accommodating a location for mounting a screw must be removed from the yoke in order to mount of the screw.
Instead of fixing a coil holder and a FPC ground wire connection portion together by means of a screw, there is a method in which a pin is press-fitted into a coil holder and the pin and a FPC connection portion are soldered together. Since a press-fit pin is smaller than a screw, such method appears to be suitable for miniaturization. In the case of adopting such method, however, there is a need for two steps, that is, a step of press-fitting of a pin and a step of soldering connection, in place of one step of screw fastening, by which workability in assembling is worsened.